National CJD Research & Surveillance Unit, Centre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, Scotland, UKInstitute for Neurodegenerative Diseases, University of California, San Francisco, San Francisco, CA

Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, Scotland, UKRoyal (Dick) School of Veterinary Studies and The Roslin Institute, University of Edinburgh, Edinburgh, Scotland, UK

Medical Research Council Centre for Regenerative Medicine, University of Edinburgh, Edinburgh, Scotland, UKUK Dementia Research Institute, University of Edinburgh, Edinburgh, Scotland, UKCentre for Clinical Brain Sciences, University of Edinburgh, Edinburgh, Scotland, UKCentre for Brain Development and Repair, Institute for Stem Cell Biology and Regenerative Medicine, National Centre for Biological Sciences, Bangalore, India